1. Field of Invention
This invention relates to switching circuits involving complementary switching elements and more particularly to methods and apparatus for reducing switching losses in such circuits.
2. Description of Related Art
Switching circuits involving complementary switching elements are commonly found in power inverters, power supplies and Class D amplifiers. In these applications, various types of switching elements may be employed. The usual choices for switching elements include Integrated Gate Bipolar Transistors (IGBTs) and Metallic Oxide Semiconductor Field Effect Transistors (MOSFETs).
MOSFETs have internal body diodes that result from their inherent design. Tradeoffs are made when designing MOSFETs, to optimize and reduce static and dynamic losses, but this often results in the creation of body diodes that have poor inherent reverse recovery characteristics that contribute to losses during reverse recovery of the devices. IGBTs have no internal body diode and typically, external diodes are used with IGBTs to control reverse recovery characteristics in a manner that reduces reverse recovery losses. IGBTs however, exhibit greater static and dynamic losses.
Thus, designers of high frequency switching circuits are faced with selecting between IGBTs and MOSFETS for use as switching elements and must make such selections by making tradeoffs between reverse recovery losses and static and dynamic losses, which can lead to an inefficient design.